Scripted email sending with attachments

send.py

#!/usr/bin/env python3

"""
Script to send emails with attachments, via gmail.
"""

# Based on a combination of:
# - https://stackoverflow.com/a/3363254/67873
# - https://github.com/PeterJCLaw/libfritter/blob/master/libfritter/mailer.py

import argparse
import getpass
import smtplib
from email.mime.application import MIMEApplication
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.utils import parseaddr

HOST = 'smtp.gmail.com'


def main(args: argparse.Namespace) -> None:
    msg = MIMEMultipart()
    msg.attach(MIMEText(args.body_file.read()))

    for attachment in args.attachments:
        msg.attach(MIMEApplication(attachment.read(), Name=attachment.name))

    # Sanity check
    parseaddr(args.sender)
    parseaddr(args.recipient)

    msg['Subject'] = args.subject
    msg['From'] = args.sender
    msg['To'] = args.recipient

    _, user = parseaddr(args.sender)
    password = args.password or getpass.getpass(
        prompt=f"Password for {user} at {HOST}: ",
    )

    # Send the message via our own SMTP server.
    with smtplib.SMTP_SSL(HOST) as s:
        s.login(user, password)
        s.send_message(msg)


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser()
    parser.add_argument('--password', required=False)
    parser.add_argument('sender')
    parser.add_argument('recipient')
    parser.add_argument('subject')
    parser.add_argument('body_file', type=argparse.FileType(mode='r'))
    parser.add_argument(
        'attachments',
        type=argparse.FileType(mode='r'),
        nargs=argparse.ZERO_OR_MORE,
    )
    return parser.parse_args()


if __name__ == '__main__':
    main(parse_args())